ota_version.h

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/*
 * SPDX-License-Identifier: LGPL-3.0-or-later
 * Copyright (c) 2026 Cryptnox SA
 */

 
#ifndef OTA_VERSION_H
#define OTA_VERSION_H
 
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>

#define OTA_VERSION_PARTS  4U

#define OTA_VERSION_MAX    32U

static inline void ota_version_parse(const char *s,
                                     unsigned long out[OTA_VERSION_PARTS])
{
    for (size_t i = 0U; i < OTA_VERSION_PARTS; i++) { out[i] = 0UL; }
    if (s == NULL) { return; }
 
    size_t i = 0U;
    if ((s[0] == 'v') || (s[0] == 'V')) { i = 1U; }
 
    size_t part = 0U;
    bool   any  = false;   /* digits seen in the current component */
    for (; (i < OTA_VERSION_MAX) && (s[i] != '\0'); i++) {
        const char c = s[i];
        if ((c >= '0') && (c <= '9')) {
            /* Clamp rather than wrap: a component this large is junk, and
             * "compares as very large" beats "compares as whatever the
             * overflow happened to leave behind". */
            if (out[part] < 100000000UL) {
                out[part] = (out[part] * 10UL) + (unsigned long)(c - '0');
            }
            any = true;
        } else if (c == '.') {
            /* A dot with no digits before it ends the number entirely — ".."
             * and a leading dot are malformed, not zero-valued components. */
            if (!any) { break; }
            part++;
            any = false;
            if (part >= OTA_VERSION_PARTS) { break; }
        } else {
            break;   /* pre-release or build suffix: ignored */
        }
    }
}

static inline int ota_version_cmp(const char *a, const char *b)
{
    unsigned long va[OTA_VERSION_PARTS];
    unsigned long vb[OTA_VERSION_PARTS];
    ota_version_parse(a, va);
    ota_version_parse(b, vb);
 
    for (size_t i = 0U; i < OTA_VERSION_PARTS; i++) {
        if (va[i] != vb[i]) { return (va[i] < vb[i]) ? -1 : 1; }
    }
    return 0;
}

#define OTA_VERSION_SHOWN_MAX  (OTA_VERSION_MAX + 2U)

static inline const char *ota_version_display(const char *v, char *buf, size_t n)
{
    if ((buf == NULL) || (n == 0U)) { return ""; }
    if (v == NULL) { v = ""; }
 
    const bool numeric = (v[0] >= '0') && (v[0] <= '9');
    (void)snprintf(buf, n, "%s%s", numeric ? "v" : "", v);
    return buf;
}
 
#endif /* OTA_VERSION_H */